Identification Resources

Key to the Major Subgroups of the Lophiiformes

The plesiomorphic and autapomorphic features of the major subgroups of the Lophiiformes are incorporated into the following analytical key:

  • 1A. Postcephalic, spinous dorsal-fin of 1 to 3 spines; pharyngobranchial IV present; cleithrum with prominent posterior spine; subopercle with large ascending process attached to anterior margin of ventral rami of opercle; pseudobranch well developed; eggs and larvae large; head of larvae small relative to body (Suborder Lophioidei)
  • 1B. Postcephalic, spinous dorsal-fin absent; pharyngobranchial IV absent; cleithral spine absent; subopercle with ascending process absent or reduced to a small projection detached from opercle; pseudobranch greatly reduced or absent; eggs and larvae small; head of larvae large relative to body (go to 2)
  • 2A. Spinous dorsal of 3 spines emerging from dorsal surface of cranium; illicial pterygiophore and pterygiophore of third dorsal-fin spine with highly compressed, blade-like dorsal expansions; interhyal with a medial, posterolaterally directed process that comes into contact with the respective preopercle; interopercle flat and broad (Suborder Antennarioidei, go to 3)
  • 2B. Spinous dorsal of 2 or 3 spines, but only anteriormost spine emerging from dorsal surface of cranium (spines II and III reduced and embedded beneath skin of head or lost); illicial pterygiophore and pterygiophore of third dorsal-fin spine without blade-like dorsal expansions; interhyal without a medial, posterolaterally directed process; interopercle elongate and narrow (go to 6)
  • 3A. Parietals meeting on the midline dorsal to supraoccipital; ectopterygoid roughly oval in shape or absent; ceratobranchials I through III with 1 or more tooth-plates; hypobranchial II simple, hypobranchial III absent; pectoral radials 2; pelvic fin of 1 spine and 4 rays (Family Brachionichthyidae)
  • 3B. Parietals well separated by supraoccipital; ectopterygoid triradiate, a dorsal process overlapping medial surface of metapterygoid; ceratobranchials I through IV toothless; hypobranchials II and III bifurcate proximally; pectoral radials 3; pelvic fin of 1 spine and 5 rays (go to 4)
  • 4A. Vomer wide, the width between lateral ethmoids nearly as great as that between lateral margins of sphenotics; vomer without posteromedial process; dorsal head of quadrate broad, the width equal to or greater than that of metapterygoid; postmaxillary process of premaxilla tapering to a point; opercle expanded posteriorly; pharyngobranchial and epibranchial of first arch toothed; bony connection between tips of haemal spines of 14th through 16th preural centra; pterygiophore of illicium elongate, greatly depressed and laterally expanded posteriorly (Family Lophichthyidae)
  • 4B. Vomer narrow, the width between lateral ethmoids considerably less than that between lateral margins of sphenotics; posteromedial process of vomer emerging from ventral surface as a laterally compressed, keel-like structure, its ventral margin (as seen in lateral view) strongly convex; dorsal head of quadrate narrow, the width less than that of metapterygoid; postmaxillary process of premaxilla spatulate; opercle reduced in size; pharyngobranchial and epibranchial of first arch toothless; bony connection between tips of haemal spines absent; pterygiophore of illicium short, the posterior end cylindrical (go to 5)
  • 5A. Eyes dorsal; dorsal-fin spines reduced; mouth small; pectoral fin double, the dorsal-most ray of ventral portion membranously attached to side of body; pectoral-fin lobe membranously attached to rays of pelvic fin; soft-dorsal fin rays 16 or 17, anal fin rays 11 or 12 (Family Tetrabrachiidae)
  • 5B. Eyes lateral; dorsal-fin spines well developed; mouth large; pectoral fin single, the rays not membranously attached to side of body; pectoral-fin lobe not membranously attached to rays of pelvic fin; soft-dorsal fin rays 11 to 15, anal fin rays 6 to 9 ( Family Antennariidae)
  • 6A. Second dorsal-fin spine elongate, embedded beneath skin of head; third dorsal spine and pterygiophore present; epibranchial I with a medial process ligamentously attached to proximal tip of epibranchial II ( Suborder Chaunacoidei)
  • 6B. Second dorsal-fin spine reduced to a tiny remnant embedded beneath skin of head and lying on, or fused to, dorsal surface of pterygiophore just behind base of illicial bone; third dorsal spine and pterygiophore absent; epibranchial I simple, without ligamentous attachment to epibranchial II (go to 7)
  • 7A. Ceratobranchial V toothed, expanded proximally; pelvic fins present; obvious sexual dimorphism absent, the males not dwarfed (Suborder Ogcocephaloidei)
  • 7B. Ceratobranchial V toothless, reduced to a slender rod-shaped element; pelvic fins absent (except in larval caulophrynids); sexual dimorphism strongly developed, the males dwarfed to a small fraction of size of females (Suborder Ceratioidei)

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